Study On Partial Discharge Characteristics And Deterioration Mechanism Of Dry-type Reactor Insulation Materials

Dry-type reactors play an important role in improving the power quality of power systems and improving their reliability.They have the advantages of simple structure and convenient maintenance.Epoxy resin cast insulation materials are widely used in dry-type reactors due to their good electrical,mechanical and chemical properties.Reactors are prone to insulation aging during design,manufacture,installation and operation,causing a series of problems such as insulation failure of dry-type reactors.Surface tracking aging and internal electrical treeing aging are the two most serious types of electrical aging.Therefore,in order to stabilize the operation of dry-type reactor,it is necessary to study the electrical aging characteristics and degradation mechanism of epoxy resin casting insulation under high voltage conditions.In this paper,epoxy resin samples prepared by self-made molds were used as experimental materials.The surface discharge of epoxy resin casting insulation materials was simulated by slanting plate method,and the internal discharge of epoxy resin casting insulation materials was simulated by needle plate electrodes.Two kinds of partial discharge detection test platforms were established.The partial discharge tester used the pulse current method to perform partial discharge detection on the epoxy resin samples through a slow and constant voltage method.The effects of two kinds of electrical aging on the insulation properties of epoxy resin insulation materials were studied by means of contact angle measurement,microscopic amplification,scanning electron microscopy and infrared Fourier analysis.The development of partial discharge characteristics of epoxy resin casting insulation materials was summarized.law.The main research work and achievements are as follows:(1)The tracking process of epoxy resin casting insulation material has experienced the initiation period,stability period,development period and explosion period,and the flashover discharge corresponding to the development period is the main reason for carbonization of insulating materials;(2)In the process of surface discharge,with the change of surface morphology and the formation of surface products,the surface roughness of materials generally presents an upward trend,and the surface roughness rises fastest during the discharge explosion period.The changes of surface morphology and three-dimensional morphology of epoxy resin materials constitute the basis for judging the insulation surface condition and the development of corrosion.(3)The discharge amount of epoxy resin shows an exponential upward trend.Adding 20wt% glass fiber and evenly distributing glass fiber,reducing the exposure of glass fiber can improve the tracking resistance of epoxy resin insulating materials.(4)The electrical treeing process of epoxy resin casting insulation material has experienced the tree initiation period,growth period,lag period and burst period.The discharge amount is small during the initiation period,the electric branch discharge amount in the growth period is stable at about 300 pC,and the discharge capacity in the lag period is decreased.The discharge amount during the explosion period is around1000pC;(5)When the curing temperature is 120 ?,the curing time is 3.0h and the glass fiber dosage is 2%,the initiation time of the electrical treeing of the composite material is prolonged,the growth rate is decreased,and the ability of restraining the growth of the electric tree is the best.Under this condition,the structure of electric tree branches is mostly complex cluster structure.Compared with pure epoxy resin,the color of the main trunk of electric tree branches becomes lighter.